@kjl, is there a reason you don’t want to use supports? They are a great way to self-fixture a part into the rawstock, and I think they will be essential when making parts using the flip jig. The only downside is that they require a little handwork to trim and sand flush after the machining. I have zero manual skills–I can injure myself eating salad with a fork–but I’m enthusiastic about using supports.
I showed some examples at Splines for 2-sided milling and included a few links over to the MeshCAM forum. They key to using supports is to place them on the widest or “equator” line of your geometry so they don’t shadow areas beneath them. That keeps the area to trim to the cross-section of the support itself.